Electronic safety ski bindings are known, e.g., see U.S. Pat. Nos. 3,907,316 and 4,291,894, having having force sensors for sensing each of the forces and torques which can typically act on the skier's leg during skiing. If a single snesor were used to detect each load the electronic safety ski bindings would be unusable when any one of the force sensors were defective or inoperative so that one of the loads could not be detected.
For this reason it is an object of the present invention to provide an electronic safety ski binding which is more reliable because its operative condition cannot be adversely affected by a failure of only individual force sensors.
In a safety ski binding of the kind described first hereinbefore this object is accomplished according to the invention by providing at least two force sensors for sensing each of the loads (forces and torques) which typically act on the leg, of a skier using the binding. Each of the two sensors is independently capable of detecting the same load so that the electronic circuit can generate, in response to the detection of a a load which may endanger the skier, a triggering signal which initiates the operation of the releasing mechanism of the binding. The reliability of the safety ski binding according to the invention is therefore considerably increased since each load can be detected even when one of the individual force sensors for each load is inoperative.
An electronic safety ski binding may also become unusable if a force sensor generates erroneous electrical signals because it is inoperative.
The reliability of an electronic safety ski binding can be further increased by eliminating erroneous signals generated by inoperative sensors. In accordance with a development of the invention, a comparator circuit is associated with each force sensor which compares the electrical signal generated by a sensor with an improbably high reference signal level and eliminates from further processing any signal which reaches the reference values as an erroneous signal. In such an embodiment, a release can be initiated only by sensor signals indicating loads in excess of the permissible forces but within reasonable ranges, or when both of the sensor pair detect an excessive load simultaneously. The latter condition would indicate a normal, highly aggressive, but short duration, load.
It should be noted that normally a bridge containing a defective sensor will generate a saturation level signal in one direction or the other.